Generally, it is common for home power sources that supply power to electronic devices (e.g., TVs, Radios, CD Radio Cassette Players, or the like) or electrical devices (e.g., power tools, or the like) to include a power source that supplies power and a converter that converts the supplied power to a voltage appropriate for use by the electronics and electrical devices, as shown in FIG. 1.
FIG. 2 illustrates one such conventional power supply device. The power supply device is configured such that it includes a converter 12 configured to convert power from power supply 10, a secondary battery 13 chargeable by voltage from the converter 12, and a DC/DC converter 11 configured to convert voltage received from the secondary battery 13 and supply power, via a terminal, to electronics and electrical devices. The power supply device charges secondary battery 13 using converter 12, which converts power received from power supply 10 to DC power. Of course, this charging occurs when it is not necessary to supply power to devices.
FIG. 3 discloses a traditional power supply device for use with electrical vehicles (EV), such as electrical cars, buses, and trains. The power supply device shown in FIG. 3 includes a converter 12 that converts power from power supply 10 into DC output power to charge secondary battery 13. When the electric vehicle is disconnected from the power supply 10, the power supply device supplies power to devices through DC/DC converter 11, which converts the DC power from the secondary battery 13.
These conventional power supply devices that include DC/DC converters (or AC/DC converters) may be sufficient for many small scale applications that do not need much power. However, for devices that require a larger power supply, using conventional technology necessitates increasing the scale of the power supply device. Increasing the size of a DC/DC converter, though, reduces the efficiency of the converter. In addition, the larger a power supply device gets, the larger its corresponding power consumption. Moreover, the inefficiencies of scale of conventional power supply devices prevent their use for transferring power between a wider array of objects.
Accordingly, it would be useful to improve the efficiency and shrink the size of power supply devices, as well as increase the flexibility of the power supply devices, such that a single system can receive power from and supply power to a variety of sources.